A sensitive, quantitative assay for measurement of allele-specific transcripts differing by a single nucleotide.

We have found that the single nucleotide primer extension assay, a PCR-based assay currently used qualitatively to measure allelic differences in DNA, can be used quantitatively to measure allele-specific transcripts differing by only a single nucleotide. We show that total RNA containing the Pgk-1a transcript can be specifically detected even in a 1000-fold excess of RNA containing the Pgk-1b transcript.